Temperature-controlled storage devices (e.g., a refrigerator, freezer, refrigerated merchandiser, display case, etc.) are used in a wide variety of commercial, institutional, and residential applications for storing and/or displaying refrigerated or frozen objects. Many temperature-controlled storage devices have a display case door (e.g., a door with an insulated glass panel) through which objects within the temperature-controlled storage device can be viewed.
Conventional insulated glass panels typically include multiple parallel panes with a layer of gas between the panes. The gas is generally air or a noble gas (e.g., Argon, Krypton, etc.) which functions as a thermal insulator to reduce heat transfer through the panel. In conventional insulated glass panels, the pressure of the air or gas between the panes is equal or substantially equal to atmospheric pressure. Reducing the pressure of the air or gas between the panes would cause atmospheric pressure to apply a large force (e.g., thousands of pounds of force) to the surface of the panel. Such a force is likely to bend or break an insulated glass panel, especially if the panel is relatively thin.
Conventional insulated glass panels typically use panes of tempered glass in order to reduce the risk of injury in the event that the panes are broken. Tempered glass has a high residual stress which adds to any atmospheric pressure applied to the surface of the panel. Additionally, the high residual stress of tempered glass can cause tempered glass panels to have an uneven (e.g., non-flat) surface. For these reasons, an evacuated space between panes (e.g., a vacuum, a reduced pressure space, etc.) has not been successfully implemented in an insulated glass panel for use with a temperature-controlled storage device.
This section is intended to provide a background or context to the invention recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.